1. Field of the Invention
The present invention relates to a light-shielding container that houses a light-sensitive material such as printing paper, light-sensitive material for printing or color negative film for photography and also to a light-sensitive material package containing the container and a light-sensitive material housed therein. In particular, the present invention relates to a light-shielding container having good light-shielding properties in the infrared region and also to a light-sensitive material package containing the container and a light-sensitive material housed therein.
2. Description of the Related Art
Photographic 35 mm roll film, etc. is used in a state in which it is housed in a light-shielding container called a cartridge. As is well known, this cartridge is essentially formed from a tubular iron shell, a spool as a core for winding the film housed in the shell into a roll form, and two caps for closing opposite ends of the shell. Moreover, a light-shielding cloth, generally called plush (also called teremp), is bonded to the inner surfaces of a film passage opening of the above-mentioned shell.
Since the light-shielding cloth is required to prevent unused film from being exposed to light and should also not interfere with the smooth drawing out and rewinding of the film, a light-shielding cloth structure having a pile being made of a flexible material on a surface of a base fabric is used as the light-shielding cloth.
Conventionally, light-shielding cloth structures of this kind are produced by weaving or knitting superimposed woven cloths or knitted cloths with a pile thread so as to combine the cloths thus giving double woven or knitted cloths, and then cutting the pile thread along a plane that is substantially central between the two woven or knitted cloths (JP-A-62-98347; JP-A denotes Japanese unexamined patent application publication). The pile of the so-called plush is in contact with the photographic film so preventing the film from being exposed to light, and its flexibility and resistance to the drawing out of photographic film are sufficient for ordinary use.
As a material for the light-shielding cloth structure, polyester thread, which is cost-efficient, has been used recently. Although the light-shielding cloth structure is usually colored black, the dyeing of polyester has problems. Polyester is a linear macromolecule formed from poly(ethylene terephthalate) and has an extremely high proportion of crystalline sections, and its non-crystalline sections are comparatively dense. Accordingly, it is a fiber having low hygroscopicity and high hydrophobicity. As is described in xe2x80x98Coloring Technologyxe2x80x99, by Tomizo Hamanaka, (Jitsukyo Publishing), etc., a water-soluble dye having a high molecular weight cannot enter a polyester fiber, thereby resulting in little dyeing of the fiber. It is mainly only hydrophobic disperse dyes having a comparatively low molecular weight that can be used as dyes for polyester.
Various types of black disperse dye suitable for dyeing polyester are commercially available from various companies. However, among these disperse dyes, none has absorption over a wide range of wavelengths that includes the infrared region. In order to improve this aspect, as described in JP-A-11-295855 a coloring agent known as an infrared absorbing agent is commercially available, but not only this is expensive but also sufficient absorption cannot be achieved at present over a wide range of wavelengths that includes the infrared region.
On the other hand, current silver halide photosensitive materials have, as is well known, various spectral sensitivities. For example, there are materials such as normal color negative films and color reversal films that are spectrally sensitized over substantially the whole visible light region (400 nm to 700 nm) and materials such as infrared films that are spectrally sensitized to the infrared region (to the long wavelength side above 700 nm, for example, 850 nm or more). When they are spectrally sensitized in the visible light region, the spectral sensitization profile differs slightly among different types of product, and the longest wavelength of the spectral sensitization thereof also differs.
It is therefore difficult to achieve sufficient light-shielding properties for all light-sensitive materials by the use of conventional light-shielding cloth, since the longest spectrally sensitive wavelength values of the light-sensitive materials vary. It is surmised that this is mainly due to the comparatively weak absorption of the conventional light-shielding cloth in the infrared region.
In order to tackle such a problem in the light-shielding properties, JU-B-37-21388 (JU-B denotes Japanese examined utility model application publication), JU-B-46-28218, JP-B-62-40696 (JP-B denotes Japanese examined patent application publication) and JP-A-2-93456 have proposed a light-shielding cloth employing black dope-dyed thread that has been colored black by incorporating carbon black into a starting thread. In general, carbon black has good light absorption over a wide range of wavelengths including ultraviolet light, visible light, and infrared light as described in JP-A-2000-35635, and the light-shielding cloth thus obtained can therefore find application with light-sensitive materials having spectral absorption in various wavelength regions. As described above, although the use of a black dope-dyed thread in a light-shielding cloth has been proposed, there is the following problem. Since carbon black is incorporated into the thread, the thickness of the black dope-dyed thread inevitably increases. When a light-shielding cloth formed from 100% of a black dope-dyed pile thread is used in a film passage opening, although light-shielding properties over a wide range of wavelengths including the ultraviolet, visible and infrared regions can be obtained, the resistance to drawing out film increases. It is thereby difficult to simultaneously satisfy requirements for the light-shielding properties and the drawing resistance.
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to provide a light-shielding container for a light-sensitive material, the container employing a light-shielding cloth that has good light-shielding properties in the infrared region and a low resistance to the drawing out of photographic film. Another object of the present invention is to provide a light-sensitive material package formed from a light-shielding container and a light-sensitive material housed therein, the container having good light-shielding properties in the infrared region and a low resistance to the drawing out of photographic film.
A first aspect of the present invention provides the following problem-solving means.
(1) A light-shielding container for a light-sensitive material, including a light-shielding cloth attached to an opening in the container through which the light-sensitive material is passed, the light-shielding cloth shielding the opening from light and including a base fabric and a pile section formed by incorporating pile threads into the base fabric, the pile section including a black dope-dyed thread pile section formed by incorporating black dope-dyed threads containing carbon black and a black-dyed thread pile section formed by incorporating black-dyed threads, wherein the proportion of the black dope-dyed thread pile section in the total pile section is 5 wt % to 60 wt %, wherein the single filament fineness of the black dope-dyed threads is thicker than that of the black-dyed threads, wherein the overall pile density of the black dope-dyed threads and the black-dyed threads is 30,000 filaments/cm2 to 55,000 filaments/cm2, and wherein the black dope-dyed thread pile section and the black-dyed thread pile section are arranged in stripes that are substantially orthogonal to the direction in which the light-sensitive material is passed.
A second aspect of the present invention provides the following problem-solving means.
(7) A light-sensitive material package including a light-shielding container for a light-sensitive material and a light-sensitive material that has sensitivity to light at 850 nm and is housed in the container, the light-shielding container for a light-sensitive material including a light-shielding cloth attached to an opening in the container through which the light-sensitive material is passed, the light-shielding cloth shielding the opening from light and including a base fabric and a pile section formed by incorporating pile threads into the base fabric, the pile section including a black dope-dyed thread pile section formed by incorporating black dope-dyed threads containing carbon black and a black-dyed thread pile section formed by incorporating black-dyed threads, wherein the proportion of the black dope-dyed thread pile section in the total pile section is 5 wt % to 60 wt %, wherein the single filament fineness of the black dope-dyed threads is thicker than that of the black-dyed threads, wherein the overall pile density of the black dope-dyed threads and the black-dyed threads is 30,000 filaments/cm2 to 55,000 filaments/cm2, and wherein the black dope-dyed thread pile section and the black-dyed thread pile section are arranged in stripes that are substantially orthogonal to the direction in which the light-sensitive material is passed.
The overall pile density in the present invention is expressed by the number of single filaments per square centimeter.